1. Field of the Technology
The technology relates to a waste toner collecting device that transports a waste toner to a collection container without blocking the waste toner, and an image forming apparatus provided with the same.
2. Description of the Related Art
Conventionally, in an image forming apparatus employing an electrophotographic system, such as a copier, printer, or the like, a photoconductor drum which is rotatably driven is charged by a charging device, an electrostatic latent image is formed on the photoconductor drum by a light irradiation according to image information, and toner particles are adhered onto the electrostatic latent image by using a developing device to form a toner image. The toner image which is made visible is then transferred onto a recording sheet by a transfer section, which is arranged along the outer periphery of the photoconductor drum, by means of a transfer electric field.
During the transfer process, all of the toner particles on the photoconductor drum are not transferred onto the recording sheet. The transfer efficiency is about 85 to 95%, although it is different depending upon a device or a transfer section. Specifically, a little amount of toner and paper powders remain on the photoconductor drum after the toner image is transferred onto the recording sheet. If a surface of the photoconductor drum having adhered thereon the remaining toner and paper powders is not cleaned, it results in a main cause for deteriorating the quality of printing when the toner image is transferred onto a next recording sheet.
Therefore, a conventional image forming apparatus is provided with a waste toner collecting device for collecting toner remaining on the photoconductor drum after the transfer of the toner image. The waste toner collecting device is mounted at a downstream side of the transfer section at the outer periphery of the photoconductor drum.
The conventional waste toner collecting device includes a cleaning section that removes the residual toner from the surface of the photoconductor drum with paper powders, and a waste toner transporting section that transports the removed toner to a collection container.
In general, the waste toner transporting section is configured to include a screw shaft in a cylindrical transporting path that connects the cleaning section and the collection container, wherein the screw shaft is rotated by a drive motor so as to transport the waste toner accumulated in the transporting path to the collection container.
The fluidity of the waste toner reduces more than that of non-used toner. Therefore, the waste toner in the waste toner transporting section adheres onto an inner face of the transporting path and the screw shaft, and the adhered toner is aggregated and grown as the image forming apparatus is used. Since a gap between the screw shaft and an inner wall face of the transporting path is small in the waste toner transporting section, the toner aggregation causes an increase in a driving load of the screw shaft.
When the driving load of the screw shaft increases to cause a non-uniform rotation, furthermore when the toner aggregation is solidified to form an agglomerate in the transporting path and the agglomerate blocks the transporting path, which hinders the rotation of the screw shaft, a blocking phenomenon occurs in which the waste toner is extraordinarily accumulated in the waste toner transporting section to thereby hinder a transporting function. Therefore, there arises a problem that the waste toner cannot be discharged, and hence, the residual toner on the surface of the photoconductor drum after the transfer cannot be cleaned. Accordingly, in the very worst case, the cleaning section is filled with the waste toner, which causes a poor cleaning of the photoconductor drum, a generation of a scratch on the surface of the photoconductor drum, and a breakdown of the waste toner collecting device.
As a countermeasure for these problems, there has been proposed an apparatus in which, for example, a screw of a screw shaft is formed from a coil-like spring member. In the apparatus, the spring member is rotated for grinding the toner aggregation by a rotational force or vibration of the spring member, in order to avoid the blocking phenomenon by facilitating the transportation of the waste toner (see, for example, Japanese Unexamined Patent Publication No. 11-84971).
However, in a method for transporting the waste toner by the coil-like spring member described above, a sufficient transporting force for transporting the waste toner and sufficient transporting amount cannot be obtained, so that the transporting efficiency is not satisfactory.